Achyronychia cooperi A.Gray

Genus and Naming

Achyronychia is a monotypic genus of flowering plant, holding only one species: Achyronychia cooperi, which has the common names onyxflower and frost-mat.

Regional Distribution

This species is native to the Mojave and Sonoran Deserts, found in northern Mexico and the U.S. states of California, Nevada, Utah, and Arizona.

California County Records

In California, it has been recorded from San Diego, Imperial, Riverside, Los Angeles, San Bernardino, and Inyo Counties.

Arizona County Records

In Arizona, it grows in Yuma, Mohave, Pima, Pinal, and Maricopa Counties.

Utah and Nevada Records

It has also been reported from Washington County, Utah, and Clark County, Nevada.

Growth Habit and Habitat

Onyxflower is a small plant that forms a low, flat mat on the ground, and grows in sandy habitat.

Stem Morphology

It sends out several prostrate stems spreading in all directions, each only a few centimeters long.

Leaf Morphology

Its thick, pale green leaves are paddle-shaped and less than 2 centimeters long.

Inflorescence

Dense clusters of tiny flowers grow in the leaf axils.

Flower Structure

These flowers have no petals, but each produces five thin, shiny white sepals that resemble small fingernails.

Genus Name Etymology

The genus name Achyronychia comes from Greek, meaning "chaff fingernail".